A USB Type-C cable is generally designed to be coupled and establish a power supply and communication line between what is termed a USB Type-C ‘source’ device and what is termed a USB Type-C ‘receiver’ device.
In theory, USB Type-C devices make it possible to achieve a bit rate of up to 10 Gb/s and to deliver, via power supply pins commonly known to those skilled in the art under the acronym ‘VBUS’, a power of up to 100 W with a maximum voltage of 20 V and a maximum current of 5 A.
Such a high electrical current of 5 A present in the USB Type-C cables generally leads to a large voltage drop. As a result, the effective voltage received on a VBUS pin of a USB Type-C receiver device is reduced.
In some cases, for example when using a long, low-quality USB Type-C cable, this reduced effective voltage may even be situated outside of the acceptable range as defined in the USB 3.1 Type-C standard.
Conventional controllers implemented in USB Type-C source devices are configured to detect voltage drops on coupled cables and to readjust reference voltages delivered on VBUS pins, so as to compensate these voltage drops.
However, this generally requires a complex implementation on silicon for such a conventional controller, as an analog-to-digital converter (ADC) and a dedicated finite state machine (FSM) are often required to recalculate these reference voltages delivered on the VBUS pins, thereby increasing the area taken up on silicon as a result.
In addition, such a controller implemented in the USB Type-C source device is configured to operate continuously. That being the case, even if no current is supplied by the cable, this controller, in particular the circuit dedicated to compensating the voltage drop on a connected cable, is always operational.
As a result, the conventional controller is not efficient in terms of performance or power consumption, in particular when there is no load or there is little load connected.